Structure-Function Relations in the Leaves of Maize and Barley: Sink-to-Source Conversion

9320218每项拟议研究都涉及利用明场、透射式电子显微镜、荧光和共聚焦激光扫描显微镜研究玉米和大麦叶片的发育和结构。发育和结构研究将得到实验研究的补充，这些实验研究旨在确定：1)源叶和库叶的光合作用途径；2)源叶和库叶韧皮部加载和卸载的位置和机制；3)与库源转换相关的结构变化；4)水分在蒸腾流中进入叶片的路径，到不同水平的叶片的中脉、小脉和横脉进行库源转换。玉米和大麦和其他草叶一样，提供了一个很好的系统来跟踪一系列细胞和亚细胞事件，正是因为叶片底部的极化细胞分裂导致了细胞发育的完全梯度。同样的系统应该是确定汇到源转换的基本机制的理想选择。玉米和大麦的叶片在结构和发育上都有许多不同的细节。与只对其中一种进行研究相比，对这两种经济上重要的牧草的叶片进行平行研究将提供更平衡的草叶结构与功能关系的图景。这些研究的结果将对作物生产力具有长期的实际意义，对于对病毒、昆虫、支原体和其他寄生虫与其宿主的关系以及杀虫剂和生长调节物质在栽培植物中的移动感兴趣的研究人员将有价值。***

9320218 Evert The proposed research involves studies on the development and structure of the leaves of maize and barley, utilizing bright- field, transmission electron, epifluorescence, and confocal laser scanning microscopy. The developmental and structural studies will be complemented by experimental studies aimed at determining: 1) the pathways followed by photoassimilates in source and sink leaves; 2) the sites and mechanisms of phloem loading and unloading in source and sink leaves, respectively; 3) the structural modifications associated with the sink-to-source conversion; and 4) the pathways followed by water, which enters the leaf in the transpiration stream, to intermediate, small, and transverse veins at various levels of leaves undergoing sink-to-source conversion. Maize and barley, as other grass leaves, provide an excellent system for following a sequence of cellular and subcellular events precisely because polarized cell division at the base of the leaf results in an unmixed gradient of cell development. This same system should be ideal for determining the underlying mechanisms of the sink-to-source transition. The leaves of maize and barley differ in many details both structurally and developmentally. Parallel studies on the leaves of both of these economically important grasses will provide a more balanced picture of structure-function relations in grass leaves than would an investigation of only one of them. The results of these studies will have long-term practical importance in relation to crop productivity and will be of value to investigators interested in relations of viruses, insects, mycoplasmas, and other parasites to their hosts and in the movement of insecticides and growth regulating substances in cultivated plants. ***